Umbricius
There is no agreement as to who Juvenal's ueteris amici is but it is tempting to consider this a pseudonym for Marcus Valerius Martialis (c. 40-104 CE), an older contemporary of Juvenal, an impoverished poet and a fellow critic of social life in Rome, from which he departed for his home in Spain sometime before 101.
While Juvenal never mentions Martial by name, Martial names Juvenal in three of his epigrams. In Ep.7.24 , Martial refers to him as Iuvenale meo, "my friend Juvenal"; in Ep. 7.91, he adresses him as facunde Iuvenalis, "eloquent Juvenal." In Ep. 12.18 , which was written from Spain (published 103 CE), Martial contrasts his rural life in his hometown, Bilbilis, with Juvenal's struggles to survive in Rome under the emperor Domitian:
While perchance you are restlessly wandering,
Juvenal, in the noisy Subura, or treading the hill of Queen Diana; while,
amid the thresholds of great men, your sweaty toga fans you, and, as you
stray, the greater Caelian [hill] and the less[er] wearies you, me my
Bilbilis, sought once more after many Decembers, has received and made a
countryman, Bilbilis, proud of its gold and iron. Here indolently, with
pleasant toil, I frequent Boterdus and Platea (such in Celtiberian lands
are the uncouth names!); I enjoy a huge unconscionable sleep which often
not even the third hour breaks, and I pay myself now in full for all my
sleeplessness for thrice ten years. Unknown is the toga; rather, when I
ask for it, the first covering at hand is given to me from a broken chair.
When I get up, a fire, served with a lordly heap of logs from the
neighbouring oak-wood, welcomes me, and my bailiff's wife crowns it with
many a pot. Next comes my huntsman, and he too a youth whom you would
desire to consort with in some secret grove. The unbearded bailiff gives
my slaves their rations, and asks permission to crop his long hair. So I
love to live, so I love to die.